How to Measure for Replacement Windows — Frame, Rough Opening, Photos
You want a number before anyone comes out, so you are standing at the window with a tape measure wondering which edge to measure from.
Reply within one business day. Or call / text 763-204-2099.
How to measure for replacement windows for a quote: measure the inside of the existing frame, jamb to jamb, at the top, middle and bottom, then head to sill at the left, center and right, and note the smallest of each. Add photos inside and out. JMB Builders uses that for a quote across the Twin Cities metro and re-measures every opening in person before ordering. Priced per opening.
- Your numbers get a quote; ours get the order
- Every opening re-measured in person before ordering
- Photo reply in one business day or free in-home estimate
Your measurements do one job: they get you a quote you can compare. They are never the numbers a window is ordered from. Before anything is ordered, JMB measures every opening in person, because a quarter inch matters on a window that is built to size and cannot be returned. So measure carefully, but do not worry about being perfect.
What you measure depends on how the window will be replaced. An insert window fits inside the old frame, so the number that matters is the inside of that frame. A full-frame replacement takes the old window out to the rough opening, the framed hole in the wall, which is hidden behind the interior casing and the exterior trim. Most homeowners cannot see the rough opening without pulling trim, and you do not need to. Measure the frame, take the photos below, and we work out which approach fits.
Rough opening and window size are not the same number. The rough opening is the framed hole. The window is built smaller than the hole so it can be shimmed plumb, square and level, with room for foam and sealant. A window ordered to the rough opening will not fit.
Get a written quote for this job
Three photos and a sentence is enough: a reply within one business day, or ask for a free in-home estimate. Or text the photos to 763-204-2099.
What you supply
- Width inside the frame, jamb to jamb, at top, middle and bottom
- Height inside the frame, head to sill, at left, center and right
- A photo of each window from inside and outside, with the tape in the shot
- A close-up of the bottom corner of the sill, inside and out
- Which rooms are bedrooms, and anything that sticks, leaks or is fogged
What JMB supplies
- A quote by opening from your measurements and photos
- An in-person measure of every opening before ordering: frame, rough opening, squareness, jamb depth
- A call on insert vs full-frame for each opening
- One order so colors and glass match
- Removal, sill pan, flashing, foam, sealant and interior trim
- Photos of the finished windows in your job folder
How it is priced: per opening
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Insert into the old frame vs. full-frame to the rough opening
- Size and style of each window
- Openings out of square, which can push a job from insert to full frame
- Rot at the sill found during the in-person measure
- Second-story access
- Interior trim: reuse, new casing or drywall returns
Number each window on a simple sketch of the house and use the same numbers on your measurements and photos. The quote lists each opening on its own line.
How long it takes
Measuring at home takes a few minutes a window. Our in-person measure of a whole house usually fits in one visit; lead time after ordering depends on the brand and is written on the quote.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized reply within one business day. Prefer a look in person? A free in-home estimate is always an option.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Measuring for an insert
Measure inside the old frame where the sashes run, three widths and three heights, and give us the smallest of each. Note if the frame looks out of square: the diagonals differ or the sash gaps are uneven.
Measuring for full frame
The rough opening is behind the trim. Measure from the outside edge of the interior casing on each side to give us the overall size, and photograph the exterior trim. We confirm the rough opening in person.
Casement, slider or picture window
Measure the same way: inside the frame for width and height. For mulled units, two or three windows joined together, measure the whole group and each window in it.
Basement windows
Measure the opening in the concrete or block, or inside the wood buck if there is one. Photograph the window well and the sill so we can see whether the bottom is wood or masonry.
How to Measure for Replacement Windows — Frame, Rough Opening, Photos: questions, answered
How do I measure for replacement windows?
Measure inside the existing frame, jamb to jamb, at the top, middle and bottom, and head to sill at the left, center and right. Write down the smallest width and smallest height. Send those with photos inside and out, and that is enough for a quote.
What is the difference between rough opening and window size?
The rough opening is the framed hole in the wall. The window is built smaller than the hole so it can be shimmed plumb and square with room for foam and sealant. Never order a window at the rough opening size.
Do I measure the glass or the frame for a replacement window?
The frame. Glass size tells you very little about what fits, because the sash and frame take up space around it. For an insert we need the inside of the frame; for full frame we need the overall trim size, and we confirm the rough opening in person.
Will my measurements be used to order the windows?
No. Your numbers get you a quote. JMB measures every opening in person before ordering, because custom-size windows are built to the number and usually cannot be returned. If our measure changes the price, we tell you before the order goes in.
How do I know if I need insert or full-frame windows?
Photos of the frame inside and out, especially the bottom corners of the sill, tell most of the story. A sound, square wood or vinyl frame can usually take an insert. Rot, an out-of-square frame or a wish for more glass usually means full frame, and we confirm it at the measure.
What should I photograph for a window replacement quote?
Each window straight on from inside and from outside, a close-up of the sill corners, and one shot with the tape across the frame. A wide photo of each side of the house helps us plan access. Number the windows so the photos and measurements match.
Recent JMB work, from our job log
59 installs recorded across 30 Twin Cities communities since Dec 2025. Window and door installs for homeowners and the builders we work with. Counts come straight from our job log; no customer names.
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Read morePage reviewed October 9, 2026 · JMB Builders LLC, MN license BC809005 · All windows pages
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Window Replacement & Installation near you
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